1. Field of the Invention
The present invention generally relates to a method for forming a metal film of a semiconductor device, and more particularly, to a method for forming a metal film on a substrate, which includes a recess such as a contact hole or a via hole.
2. Description of the Related Art
The rapid development of information process apparatuses has necessitated the development of semiconductor devices having high operational speed and large storage capacity. Such semiconductor devices have a high integration density, improved reliability, and rapid response speed. These are only several examples of the advantageous attributes attributed to such advanced semiconductor devices.
Regarding the design of a semiconductor device, a metal wiring thereof should have a low electrical resistance and high reliability. Using relatively inexpensive metal wiring helps reduce manufacturing costs. Therefore, aluminum is normally used to form the metal wiring. Recent semiconductor devices require may follow a design rule of below approximately 0.15 μm, and the contact or via hole may be required to have a high aspect ratio. Therefore, a method for sufficiently filling the contact or via hole with an aluminum wiring has been developed.
For example, one such method includes forming an aluminum film directly on a substrate that has a recess such as a contact or via hole, in order to fill the recess by utilizing the re-flow characteristics of the aluminum. This method effectively fills the recess with the aluminum. However, because the aluminum film is rapidly deposited at the entrance of the recess, which has a high aspect ratio, the recess entrance may be blocked. Moreover, the aluminum forming method may create undesirable voids in the recess.
Another method for filling a recess with aluminum requires selectively depositing aluminum on an insulation film and on a conductive film, such as a metal barrier layer. The method can be employed for filling a via hole. However, the method need not be used for filling a contact hole that includes a conductive film, such as a metal barrier layer.
Therefore, a method for completely filling a metal film in a contact hole, while concurrently reducing a contact resistance and an electrical resistance of a wiring has been developed. The method includes selectively forming an anti-nucleation layer (ANL) on a substrate to achieve the aforementioned reductions. An example of such a method is disclosed in U.S. Pat. No. 6,001,420 (issued to Mosely el al.), Korean Patent No. 269,878, Korean Laid Open Patent Publication No. 2001-73825, and Japanese Laid Open Patent Publication No. 2001-168101.
According to the disclosure in Korean Patent No. 269,878, after forming an anti-nucleation layer on a substrate, while avoiding a recess thereof, an aluminum film is continuously formed on a bottom surface and sidewalls of the recess. Then, an aluminum film is formed on the substrate and recess using a sputtering process. This ensures that the recess is filled with the aluminum film. Next, a highly oxidative metal film is formed and, thereafter, the ANL is formed by oxidizing a metal film. This additional oxidation process required for forming the ANL reduces the productivity of the recess filling process.
U.S. Pat. No. 6,001,420 discloses a method for filling a recess with an aluminum film, which includes forming an ANL and an aluminum film in-situ. It is asserted that the method improves the productivity of the recess filling process. According to the '420 patent, the ANL is formed using dimethlyaluminum hydride (DMAH) and a nitrogen gas without a plasma, and the aluminum film for filling the recess is formed by a chemical vapor deposition process. However, forming the ANL is less effective without the use of plasma. Furthermore, the use chemical vapor deposition generally does not fill the recess with aluminum film. The chemical vapor deposition process forms an aluminum film that has a liner shape, which is continuously formed on the bottom surface and on the sidewalls of the recess. As a result, processing failures may occur even though the productivity may be improved.